Light guide with patterned ink

ABSTRACT

A light-emitting device comprising: a light source; and a light guide that is optically coupled to the light source, the light guide including a plurality of first non-fluorescent light extraction elements and a plurality of second non-fluorescent light extraction elements that are printed on the light guide, each of the first light extraction elements having a reflectance that is higher than a reflectance of any of the second light extraction elements, each of the first light extraction elements having a light transmittance that is lower than a light transmittance of any the second light extraction elements, each of the first light extraction elements having the same shape and size as any other one of the plurality first light extraction elements, and each of the second light extraction elements having the same shape and size as any other one of the plurality of second light extraction elements.

CROSS REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of U.S. patent application Ser. No.16/534,684, filed on Aug. 7, 2019, which is a continuation of U.S.patent application Ser. No. 15/785,340, filed on Oct. 16, 2017, whichclaims the benefit of U.S. Patent Provisional Application No.62/432,488, filed on Dec. 9, 2016. This application also claims thebenefit of priority to European Patent Application No. 17155827.3, filedon Feb. 13, 2017. All above-listed applications are incorporated byreference in their entireties.

FIELD OF INVENTION

The present disclosure relates to light emitting devices in general, andmore particularly, to a light guide with patterned ink.

BACKGROUND

Light emitting diodes (“LEDs”) are commonly used as light sources invarious applications. LEDs are more energy-efficient than traditionallight sources, providing much higher energy conversion efficiency thanincandescent lamps and fluorescent light, for example. Furthermore, LEDsradiate less heat into illuminated regions and afford a greater breadthof control over brightness, emission color and spectrum than traditionallight sources. These characteristics make LEDs an excellent choice forvarious lighting applications, such as outdoor lighting, decorativelighting, or outdoor lighting.

Different applications require different light distribution patterns.This necessitates LEDs to be paired with the appropriate light fixturewhen used for indoor or outdoor lighting. For example, some indoorlighting applications may require light emissions in both the upward anddownward directions, whereas others may require a light emission to beproduced only in the downward direction. As another example, someoutdoor lighting applications may require light emissions that are morebroadly spread than others. Accordingly, the need exists for LED-basedlight fixture designs that are capable of producing a wide variety oflight distribution patterns without major modification.

SUMMARY

The present disclosure addresses this need. According to aspects of thedisclosure, a light-emitting device is disclosed comprising: a lightsource; and a light guide that is optically coupled to the light source,the light guide including a plurality of first non-fluorescent lightextraction elements and a plurality of second non-fluorescent lightextraction elements that are printed on the light guide, each of thefirst light extraction elements having a reflectance that is higher thana reflectance of any of the second light extraction elements, each ofthe first light extraction elements having a light transmittance that islower than a light transmittance of any the second light extractionelements, each of the first light extraction elements having the sameshape and size as any other one of the plurality first light extractionelements, and each of the second light extraction elements having thesame shape and size as any other one of the plurality of second lightextraction elements.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings described below are for illustration purposes only. Thedrawings are not intended to limit the scope of the present disclosure.Like reference characters shown in the figures designate the same partsin the various embodiments.

FIG. 1 is a schematic side view of an example of a light fixture,according to the prior art;

FIG. 2 is a schematic side view of an example of a light fixture,according to aspects of the disclosure;

FIG. 3 is a schematic side view of an example of a light fixture,according to aspects of the disclosure;

FIG. 4A is a schematic top-down view of an example of a light guideassembly, according to aspects of the disclosure;

FIG. 4B is a schematic side view of the light guide assembly of FIG. 4A,according to aspects of the disclosure;

FIG. 4C is a candela diagram illustrating a light distribution patternproduced by the light guide assembly of FIG. 4A, according to aspects ofthe disclosure;

FIG. 5A is a schematic top-down view of an example of a light guideassembly, according to aspects of the disclosure;

FIG. 5B is a schematic side view of the light guide assembly of FIG. 5A,according to aspects of the disclosure;

FIG. 5C is a candela diagram illustrating a light distribution patternproduced by the light guide assembly of FIG. 5A, according to aspects ofthe disclosure;

FIG. 6A is a schematic top-down view of an example of a light guideassembly, according to aspects of the disclosure;

FIG. 6B is a schematic side view of the light guide assembly of FIG. 6A,according to aspects of the disclosure;

FIG. 6C is a candela diagram illustrating a light distribution patternproduced by the light guide assembly of FIG. 6A, according to aspects ofthe disclosure;

FIG. 7A is a schematic top-down view of an example of a light guideassembly, according to aspects of the disclosure;

FIG. 7B is a schematic side view of the light guide assembly of FIG. 7A,according to aspects of the disclosure;

FIG. 7C is a candela diagram illustrating a light distribution patternproduced by the light guide assembly of FIG. 7A, according to aspects ofthe disclosure;

FIG. 8A is a schematic top-down view of an example of a light guideassembly, according to aspects of the disclosure;

FIG. 8B is a schematic side view of the light guide assembly of FIG. 8A,according to aspects of the disclosure;

FIG. 8C is a candela diagram illustrating a light distribution patternproduced by the light guide assembly of FIG. 8A, according to aspects ofthe disclosure;

FIG. 9A is a schematic top-down view of an example of a light guideassembly, according to aspects of the disclosure;

FIG. 9B is a schematic side view of the light guide assembly of FIG. 9A,according to aspects of the disclosure;

FIG. 9C is a candela diagram illustrating a light distribution patternproduced by the light guide assembly of FIG. 9A, according to aspects ofthe disclosure;

FIG. 10A is a schematic top-down view of an example of a light guideassembly, according to aspects of the disclosure;

FIG. 10B is a schematic side view of the light guide assembly of FIG.10A, according to aspects of the disclosure;

FIG. 10C is a candela diagram illustrating a light distribution patternproduced by the light guide assembly of FIG. 10A, according to aspectsof the disclosure;

FIG. 11A is a schematic top-down view of an example of a light guideassembly, according to aspects of the disclosure;

FIG. 11B is a schematic side view of the light guide assembly of FIG.11A, according to aspects of the disclosure;

FIG. 11C is a candela diagram illustrating a light distribution patternproduced by the light guide assembly of FIG. 11A, according to aspectsof the disclosure;

FIG. 12A is a schematic top-down view of an example of a light guideassembly, according to aspects of the disclosure;

FIG. 12B is a schematic side view of the light guide assembly of FIG.12A, according to aspects of the disclosure;

FIG. 12C is a candela diagram illustrating a light distribution patternproduced by the light guide assembly of FIG. 12A, according to aspectsof the disclosure;

FIG. 13A is a schematic top-down view of an example of a light guideassembly, according to aspects of the disclosure;

FIG. 13B is a schematic side view of the light guide assembly of FIG.13A, according to aspects of the disclosure;

FIG. 13C is a candela diagram illustrating a light distribution patternproduced by the light guide assembly of FIG. 13A, according to aspectsof the disclosure;

FIG. 14 is a schematic top-down view of an example of a light guideassembly, according to aspects of the disclosure; and

FIG. 15 is a candela diagram illustrating a light distribution patternproduced by the light guide assembly of FIG. 14, according to aspects ofthe disclosure.

DETAILED DESCRIPTION

According to aspects of the disclosure, an improved light fixture isdisclosed comprising a light guide that has at least two different typesof light extraction elements (e.g., Gaussian dots) printed thereon. Thetwo types of light extraction elements may differ from one another in atleast one of the following characteristics: (1) light transmissivity,(2) light reflectance, (3) size, (4) shape, (5) distribution density,and (6) color. The light extraction elements may be printed on thesurface(s) of the light guide by using different types of ink.

According to aspects of the disclosure, the improved light fixture mayproduce a wide variety of light distribution patterns without majormodification. By adjusting the (1) spatial arrangement, (2) distributiondensity, (3) relative locations, and/or (4) relative size of differenttypes of light extraction elements that are printed on the fixture'slight guide, many different light distribution patterns can be achieved.In this regard, the light distribution pattern produced by the improvedlight fixture may be changed by simply printing a different lightextraction pattern on the fixture's light guide. This permits the lightfixture to produce a wide variety of light distribution patterns withoutmajor structural modifications.

According to aspects of the disclosure, the improved light fixture mayuse reflector(s) to further shape the effect of the light extractionelements that are printed on the fixture's light guide. For example, insome implementations, a single reflector may be placed on one surface ofthe light guide to reflect all light that is extracted by the lightextraction elements in the same direction. As another example, in someimplementations, one reflector may be placed on a portion of one surfaceof the light guide to force light extracted by one type of lightextraction elements in a first direction, while another reflector may beplaced on a portion of a second surface of the light guide to forcelight extracted by a second type of light extraction elements in asecond direction that is opposite to the first direction.

According to aspects of the disclosure, a light-emitting device isdisclosed comprising: a light source; and a light guide that isoptically coupled to the light source, the light guide including aplurality of first non-fluorescent light extraction elements and aplurality of second non-fluorescent light extraction elements that areprinted on the light guide, each of the first light extraction elementshaving a reflectance that is higher than a reflectance of any of thesecond light extraction elements, each of the first light extractionelements having a light transmittance that is lower than a lighttransmittance of any the second light extraction elements, each of thefirst light extraction elements having the same shape and size as anyother one of the plurality first light extraction elements, and each ofthe second light extraction elements having the same shape and size asany other one of the plurality of second light extraction elements.

According to aspects of the disclosure, a light-emitting device isdisclosed comprising: a light source; and a light guide that isoptically coupled to the light source, the light guide including firstgroup of first light extraction elements printed on the light guideadjacently to a first edge of the light guide, a second group of firstlight extraction elements printed adjacently to a second edge of thelight guide that is opposite the first edge, and a third group of secondlight extraction elements printed on the light guide between the firstgroup and the second group, each of the first light extraction elementshaving a reflectance that is higher than a reflectance of any of thesecond light extraction elements, and each of the first light extractionelements having a light transmittance that is lower than a lighttransmittance of any the second light extraction elements.

A light-emitting device is disclosed comprising: a light source; and alight guide that is optically coupled to the light source, the lightguide including a first grid pattern of first light extraction elementsthat is printed on the light guide, and a second grid pattern of secondlight extraction elements, at least some of the second light extractionelements being positioned in an interstice between four different secondlight extraction elements, each of the second light extraction elementsbeing greater in size than any of the first light extraction elements,each of the first light extraction elements having a reflectance that ishigher than a reflectance of any of the second light extractionelements, and each of the first light extraction elements having a lighttransmittance that is lower than a light transmittance of any the secondlight extraction elements.

Examples of different systems will be described more fully hereinafterwith reference to the accompanying drawings. These examples are notmutually exclusive, and features found in one example can be combinedwith features found in one or more other examples to achieve additionalimplementations. Accordingly, it will be understood that the examplesshown in the accompanying drawings are provided for illustrativepurposes only and they are not intended to limit the disclosure in anyway. Like numbers refer to like elements throughout.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, these elements should notbe limited by these terms. These terms are only used to distinguish oneelement from another. For example, a first element could be termed asecond element, and, similarly, a second element could be termed a firstelement, without departing from the scope of the present invention. Asused herein, the term “and/or” includes any and all combinations of oneor more of the associated listed items.

It will be understood that when an element such as a layer, region orsubstrate is referred to as being “on” or extending “onto” anotherelement, it can be directly on or extend directly onto the other elementor intervening elements may also be present. In contrast, when anelement is referred to as being “directly on” or extending “directlyonto” another element, there are no intervening elements present. Itwill also be understood that when an element is referred to as being“connected” or “coupled” to another element, it can be directlyconnected or coupled to the other element or intervening elements may bepresent. In contrast, when an element is referred to as being “directlyconnected” or “directly coupled” to another element, there are nointervening elements present. It will be understood that these terms areintended to encompass different orientations of the element in additionto any orientation depicted in the figures.

Relative terms such as “below” or “above” or “upper” or “lower” or“horizontal” or “vertical” may be used herein to describe a relationshipof one element, layer or region to another element, layer or region asillustrated in the figures. It will be understood that these terms areintended to encompass different orientations of the device in additionto the orientation depicted in the figures.

FIG. 1 is a diagram of an example of a light fixture 22, according tothe prior art. The fixture includes a light guide plate 11 having aplurality of light scattering dots 24 printed on a surface 12 c of thelight guide plate. A reflective film 16 is placed over the lightscattering dots 24 to reflect light in an upwards direction towards asurface 12 b of the light guide plate 11. An optical film 20 ispositioned on the surface 12 b of the light guide plate 11 to conditionany light that exits the surface 12 b. The optical film 20 may include adiffusion film, a prism film, and/or a brightness enhancement film. Alight source 14 is coupled to the edge 12 a of the light fixture 22, asshown. The light source 14 may include a light source part 14A (e.g., alight-emitting diode) and a reflector 14B arranged to face the edge 12 aof the light fixture 22.

FIG. 2 is a diagram of an example of a light fixture including a lightguide 30, according to aspects of the disclosure. In this example, alight source is edge-coupled to the light guide 30, as shown. The lightsource includes an LED chip 104 that is disposed on a mount 102 andarranged to face in the direction of the edge of the light guide 30, asshown. A lens 106 may be disposed between the LED chip 104 and the lightguide 30 to extract light 108 emitted from the LED chip 104substantially uniformly in all directions except in the direction thatis opposite the LED chip from the lens.

FIG. 3 is a diagram of another example of a light fixture that includesthe light guide 30. In this example, a light source is disposed in acavity 110 formed in the light guide 30, as shown. The light sourceincludes an LED chip 114 that is arranged on a mount 112. The mount 112is disposed over the opening of the cavity 110, such that the LED chip114 fits entirely within the cavity. In operation, the LED chip 114emits light 116 which may enter the light guide 30 through the walls ofthe cavity.

As illustrated in FIGS. 2 and 3, LEDs can either be edge-coupled to thelight guide 30 or disposed in a cavity that is formed in the light guide30. Although the fixtures shown in FIGS. 2 and 3 include only one LED,it can be readily appreciated that alternative implementations arepossible in which a larger number of LEDs are included in either one ofthe fixtures. In this regard, the present disclosure is not limited toany specific number of LEDs and/or a manner of coupling the LEDs to thelight guide 30 in different light guide assemblies that are discussedfurther below.

According to aspects of the disclosure, the light guide 30 may include aplate having a thickness between 1 mm and 8 mm. The plate may be formedof glass, plastic, PMMA, polycarbonate, and/or any other suitable typeof material. Moreover, in some implementations, the light guide may beformed of a material that is transparent and/or non-degrading whensubjected to desired operating conditions. The plate may have two majorsurfaces and a plurality of edges. In some implementations, duringnormal operation of the light guide, light may be emitted from one orboth of the major surfaces of the light guide, while the edges mayoptionally be hidden inside a housing enclosure, a trim, and/or anyother suitable element.

According to aspects of the disclosure, the light guide 30 may beprovided with different light extraction patterns, examples of which aredepicted in FIGS. 4A-15. Those extraction patterns may each includelight extraction elements 36 and light extraction elements 38. In someimplementations, each of the light extraction elements 38 may have 45%light reflectance and 55% light transmittance and a 15° Gaussiandiffusion pattern. Additionally or alternatively, in someimplementations, each of the light extraction elements 36 may have 90%light reflectance and 10% light transmittance. As is discussed furtherbelow, the light extraction elements 36 and 38 may alter the pattern inwhich light travels through the light guide 30, such that the light isextracted in a preferred direction and/or in a preferred emissionpattern.

The light extraction elements 36 and 38 may be printed on one or more ofthe major surfaces of the light guide 30 (e.g., surfaces 32 and/or 34).The light extraction elements 36 may be printed using a first ink, andthe light extraction elements 38 may be printed using a second ink. Insome implementations, the second ink may have 45% light reflectance and55% light transmittance, and a 15° Gaussian diffusion pattern.Additionally or alternatively, in some implementations, the first inkmay have 90% light reflectance and 10% light transmittance. The lightextraction elements 36 and 38 may be printed using any suitable type ofprinting technology, such as ink jet printing.

The light extraction elements 36 and/or 38 may have any suitable type ofshape. For example, each of the light extraction elements 36 in a givenlight fixture (or light guide) may have a circular shape and diameter inthe range of 0.01 mm to 3 mm. Additionally or alternatively, each of thelight extraction elements 38 in a given light fixture (or light guide)may have a circular shape and diameter in the range of 0.01 mm to 3 mm.In some implementations, the light extraction elements 36 and 38 in agiven light fixture (or light guide) may have the same shape.Additionally or alternatively, in some implementations, the lightextraction elements 36 and 38 in a given light fixture (or light guide)may have different shapes. In some implementations, the light extractionelements 36 and 38 in a given light fixture (or light guide) may be thesame size. Additionally or alternatively, in some implementations, thelight extraction elements 36 in a given light fixture (or light guide)may be smaller or larger than the light extraction elements 38 in thesame fixture. FIGS. 4A-15, which are discussed further below, illustrateexamples of different light extraction patterns that can be constructedby mixing the light extraction elements 36 and 38.

More specifically, FIGS. 4A-15, which are discussed further below,provide examples of different light guide assemblies. These light guideassemblies include a light guide 30 and various light extractionpatterns that are printed on the light guide 30. The light sources(e.g., LEDs) that are used to inject light into the light guideassemblies are omitted for clarity. However, it will be understood thatany suitable arrangement for introducing light into the light guideassemblies may be used. The present disclosure, is thus not limited tothe techniques for injecting light into a light guide, examples of whichare illustrated in FIGS. 2 and 3. Furthermore, it will be noted thatdepictions of light reflectors are omitted from top-down views of lightguide assemblies which include such reflectors in order to reveal lightextraction patterns that are formed underneath the reflectors. Lightrays emitted from the guide light assemblies are depicted as arrowsoriginating from the light guide assemblies.

FIGS. 4A-B are diagrams of an example of a light guide assembly 400,according to aspects of the disclosure. The light guide assembly 400includes a light guide 30 and a diffusive reflector 40 disposedadjacently to a surface 34 of the light guide 30. A plurality of lightextraction elements 36 are formed on the surface 34 between the lightguide 30 and the diffusive reflector 40. FIG. 4C is a candela diagramshowing the light distribution pattern produced by the light guideassembly 400. As illustrated, the light guide assembly 400 is configuredto produce a Lambertian light distribution pattern in the downwarddirection.

FIGS. 5A-B are diagrams of an example of a light guide assembly 500,according to aspects of the disclosure. The light guide assembly 500includes a light guide 30 and a specular reflector 42 disposedadjacently to a surface 34 of the light guide 30. A plurality of lightextraction elements 38 are formed on the surface 34 between the lightguide 30 and the specular reflector 42. FIG. 5C is a candela diagramshowing the light distribution pattern produced by the light guideassembly 500. As illustrated, the light guide assembly 500 is configuredto produce a batwing light distribution pattern in the downwarddirection.

Each of the light guide assemblies 400 and 500 uses only one type oflight extraction elements. The light guide assembly 400 includes onlylight extraction elements 36, whereas the light guide assembly 600includes only light extraction elements 38. In some aspects, thedifference in the resultant light distribution patterns produced by thelight guide assemblies 400 and 500, respectively, is at least in partattributable to the type of light extraction elements used in each lightguide assembly. Specifically, when the light extraction elements 36 areused alone, they tend to produce a Lambertian light distributionpattern. By contrast, when the light extraction elements 38 are usedalone, they tend to produce a batwing light distribution pattern.

FIGS. 6A-B are diagrams of an example of a light guide assembly 600,according to aspects of the disclosure. The light guide assembly 600includes a light guide 30 and a plurality of light extraction elements36 formed on the surface 34 of the light guide 30, as shown. FIG. 6C isa candela diagram showing the light distribution pattern produced by thelight guide assembly 600. As illustrated, the light guide assembly 600is configured to produce a Lambertian light distribution pattern in boththe upward and downward directions. This is in contrast to the lightguide assembly 500 which uses a diffusive reflector to force all emittedlight in the downward direction.

FIGS. 7A-B are diagrams of an example of a light guide assembly 700,according to aspects of the disclosure. The light guide assembly 700includes a light guide 30 and a plurality of light extraction elements38 formed on the surface 34 of the light guide 30, as shown. FIG. 7C isa candela diagram showing the light distribution pattern produced by thelight guide assembly 700. As illustrated, the light guide assembly 700is configured to produce a batwing light distribution pattern in boththe upward and downward directions.

As discussed above, the light extraction elements 36, when used alone,tend to produce a Lambertian light distribution pattern (e.g., see FIGS.4A-C), whereas the light extraction elements 38 tend to produce abatwing light distribution pattern when used alone (e.g., see FIGS.5A-C). In some aspects, the light distribution pattern produced by aparticular light guide may be fine-tuned by selectively mixing the lightextraction elements 36 and 38. For example, introducing a minority oflight extraction elements 38 in a light guide that includes a majorityof light extraction elements 36 may produce a modified Lambertian lightdistribution pattern that has a slightly wider spread than otherwise(e.g., see FIGS. 8A-C). Similarly, introducing a minority of lightextraction elements 36 in a light guide that includes a majority oflight extraction elements 38 may produce a modified batwing lightdistribution pattern that has a more pronounced middle section thanotherwise (e.g., see FIGS. 9A-C).

FIGS. 8A-B are diagrams of an example of a light guide assembly 800,according to aspects of the disclosure. The light guide assembly 800includes a light guide 30 and a diffusive reflector 40 disposedadjacently to a surface 34 of the light guide 30. A light extractionpattern is formed on the surface 34 of the light guide 30 that includesboth light extraction elements 36 and light extraction elements 38. FIG.8C is a candela diagram showing the light distribution pattern producedby the light guide assembly 800. As illustrated, the light guideassembly 800 is configured to produce a modified Lambertian lightdistribution pattern in the downward direction.

The light extraction pattern of the light guide assembly 800 includes aplurality of columns C. Each column C may include an alternatingsequence of three light extraction elements 36 followed by one lightextraction element 38. Each column C may be shifted with respect to itsneighboring columns C by one spot 51 which may roughly correspond to thefootprint of an individual light extraction element. Alternatively, thelight extraction pattern of the light guide assembly 800 can bedescribed as an alternating sequence including two rows R1 followed byone row R2 and one row R3. Each row R1 may include only light extractionelements 36. Each row R2 may include an alternating sequence of onelight extraction element 36 followed by one light extraction element 38.Each row R3 may include an alternating sequence of one light extractionelement 38 followed by one light extraction element 36. In some aspects,both light extraction elements 36 and 38 may be distributed uniformlyacross the surface 34 of the light guide 30, with the light extractionelements 36 having a three-times greater distribution density than thelight extraction elements 38.

According to aspects of the disclosure, all light extraction elements 36in the light guide assembly 800 may have the same shape (e.g., acircular or dot shape) and the same size (e.g., a size in the range of0.01 mm-3 mm). Additionally or alternatively, all light extractionelements 38 in the light guide assembly 800 may have the same shape(e.g., a circular or dot shape) and the same size (e.g., a size in therange of 0.01 mm-3 mm). Moreover, in the example of FIGS. 8A-C, eachlight extraction element 36 has the same size and/or shape as any of thelight extraction elements 38. However, alternative implementations arepossible in which each of the light extraction elements 36 has adifferent size than any of the light extraction elements 38.Additionally or alternatively, further implementations are possible inwhich each of the light extraction elements 36 has a different shapethan any of the light extraction elements 38. As discussed above, insome implementations, the light extraction elements 36 may differ intheir respective light reflectance and transmittance. By way of example,each of the light extraction elements 38 may have 45% light reflectanceand 55% light transmittance, and a 15° Gaussian diffusion pattern, andthe light extraction elements 36 may each have 90% light reflectance and10% light transmittance. Furthermore, in some implementations, each ofthe light extraction elements 36 and/or 38 may have a uniformreflectance and transmittance. And still furthermore, in someimplementations, each of the light extraction elements 36 and 38 may benon-fluorescent.

As noted above, unlike the light guide assembly 400, the lightextraction pattern of the light guide assembly 800 includes a minorityof light extraction elements 38 that are interleaved with a majority oflight extraction elements 36. The interleaving of a minority the lightextraction elements 38 with a majority of light extraction elements 36may result in a wider Lambertian light distribution pattern. Thisconcept is illustrated by FIGS. 4C and 8C which show that the lightdistribution pattern of the light guide assembly 800 has a slightlywider emission spread than the light distribution pattern of the lightguide assembly 400.

FIGS. 9A-B are diagrams of an example of a light guide assembly 900,according to aspects of the disclosure. The light guide assembly 900includes a light guide 30 and a specular reflector 42 disposedadjacently to a surface 34 of the light guide 30. A light extractionpattern is formed on the surface 34 of the light guide 30 that includesboth light extraction elements 36 and light extraction elements 38. FIG.9C is a candela diagram showing the light distribution pattern producedby the light guide assembly 900. As illustrated, the light guideassembly 800 is configured to produce a modified batwing lightdistribution pattern in the downward direction.

The light extraction pattern of the light guide assembly 900 includes aplurality of columns C. Each column C includes an alternating sequenceof three light extraction elements 38 followed by one light extractionelement 36. Each column C is shifted with respect to its neighboringcolumns C by one spot 51 which may roughly correspond to the footprintof an individual light extraction element. Alternatively, the lightextraction pattern of the light guide assembly 900 can be described asan alternating sequence including two rows R1 followed by one row R2 andone row R3. Each row R1 may include only light extraction elements 38.Each row R2 may include an alternating sequence of one light extractionelement 36 followed by one light extraction element 38. Each row R3 mayinclude an alternating sequence of one light extraction element 38followed by one light extraction element 36. In some aspects, both thelight extraction elements 36 and 38 may be distributed uniformly acrossthe surface 34 of the light guide 30, with the light extraction elements36 having a three-times greater distribution density than the lightextraction elements 38.

According to aspects of the disclosure, all light extraction elements 36in the light guide assembly 900 may have the same shape (e.g., acircular or dot shape) and the same size (e.g., a size in the range of0.01 mm-3 mm). Additionally or alternatively, all light extractionelements 38 in the light guide assembly 900 may have the same shape(e.g., a circular or dot shape) and the same size (e.g., a size in therange of 0.01 mm-3 mm). Moreover, in the example of FIGS. 9A-C, eachlight extraction element 36 has the same size and/or shape as any of thelight extraction elements 38. However, alternative implementations arepossible in which each of the light extraction elements 36 has adifferent size than any of the light extraction elements 38.Additionally or alternatively, further implementations are possible inwhich each of the light extraction elements 36 has a different shapethan any of the light extraction elements 38. As discussed above, insome implementations, the light extraction elements 36 may differ intheir respective light reflectance and transmittance. By way of example,each of the light extraction elements 38 may have 45% light reflectanceand 55% light transmittance, and a 15° Gaussian diffusion pattern, andthe light extraction elements 36 may each have 90% light reflectance and10% light transmittance. Furthermore, in some implementations, each ofthe light extraction elements 36 may have a uniform reflectance andtransmittance. Similarly, in some implementations, each of the lightextraction elements 38 may have a uniform reflectance and transmittance.And still furthermore, in some implementations, each of the lightextraction elements 36 and 38 may be non-fluorescent.

As noted above, unlike the light guide assembly 500, the lightextraction pattern of the light guide assembly 900 includes a minorityof light extraction elements 36 that are interleaved with a majority oflight extraction elements 38. The interleaving of a minority the lightextraction elements 36 with a majority of light extraction elements 38results in a modified batwing light distribution pattern which has amore pronounced middle section. This concept is illustrated by FIGS. 5Cand 9C which show that the light distribution pattern of the light guideassembly 900 has a more pronounced middle section than the lightdistribution pattern of the light guide assembly 500.

In the examples of FIGS. 8A-C and 9A-C, the light extraction elements 36are interleaved with the light extraction elements 38. However, in someimplementations, the light extraction elements 36 and 38 may besegregated into separate groups, each group including light extractionelements of one kind only (e.g., see FIGS. 10A-C and FIGS. 11A-C). Anytwo neighboring groups may be spaced apart from one another by adistance that is greater than the distance between any two lightextraction elements within any of the groups. Each group may include anynumber of light extraction elements. Furthermore, each group may beoriented in any direction relative to the light guide it is printed on(e.g., oriented along the length of the light guide, oriented along thewidth of the light guide, etc.). FIGS. 10A-C and FIGS. 11A-C, which arediscussed further below, provide specific examples of light extractionpatterns in which the light extraction elements 36 and 38 are organizedinto separate groups.

FIGS. 10A-B are diagrams of an example of a light guide assembly 1000,according to aspects of the disclosure. The light guide assembly 1000includes a light guide 30 and a light extraction pattern formed on asurface 34 of the light guide 30. The light extraction pattern includesa group G1 of light extraction elements 36 disposed between two groupsG2 of light extraction elements 38. Although in the present example thegroup G1 includes six columns of light extraction elements, alternativeimplementations are possible in which the group G1 includes any numberof columns of light extraction elements (e.g., 1, 2, 5, 15, etc.).Although in the present example the groups G2 each include one column oflight extraction elements, alternative implementations are possible inwhich each of the groups G2 includes any number of columns of lightextraction elements (e.g., 2, 4, 7, etc.). Although in the presentexample the light extraction pattern of the light guide 30 includes onlythree groups of light extraction elements (e.g., two groups G2 and onegroup G1 of light extraction elements), alternative implementations arepossible in which the light guide 30 includes any number of lightextraction element groups (e.g., 2, 4, 5, 10, 15, etc.).

FIG. 10C is a candela diagram showing the light distribution patternproduced by the light guide assembly 1000. As illustrated, the lightguide assembly 1000 is configured to produce a modified Lambertian lightdistribution pattern both in the upward and downward directions. Thislight distribution pattern has a wider emission spread than the lightdistribution pattern produced by the light guide assembly 600. Thisdifference is attributable to the introduction of a minority of lightextraction elements 38 that are arranged in groups along opposite edgesof the light guide 30. Although in the present example, the groups G2are arranged along the longer edges of the light guide 30, alternativeimplementations are possible in which the groups G2 are arranged alongthe shorter edges.

According to aspects of the disclosure, all light extraction elements 36in the light guide assembly 1000 may have the same shape (e.g., acircular or dot shape) and the same size (e.g., a size in the range of0.01 mm-3 mm). Additionally or alternatively, all light extractionelements 38 in the light guide assembly 1000 may have the same shape(e.g., a circular or dot shape) and the same size (e.g., a size in therange of 0.01 mm-3 mm). Moreover, in the example of FIGS. 10A-C, eachlight extraction element 36 has the same size and/or shape as any of thelight extraction elements 38. However, alternative implementations arepossible in which each of the light extraction elements 36 has adifferent size than any of the light extraction elements 38.Additionally or alternatively, further implementations are possible inwhich each of the light extraction elements 36 has a different shapethan any of the light extraction elements 38. As discussed above, insome implementations, the light extraction elements 36 may differ intheir respective light reflectance and transmittance. By way of example,each of the light extraction elements 38 may have 45% light reflectanceand 55% light transmittance, and a 15° Gaussian diffusion pattern, andthe light extraction elements 36 may each have 90% light reflectance and10% light transmittance. Furthermore, in some implementations, each ofthe light extraction elements 36 may have a uniform reflectance andtransmittance. Similarly, in some implementations, each of the lightextraction elements 38 may have a uniform reflectance and transmittance.And still furthermore, in some implementations, each of the lightextraction elements 36 and 38 may be non-fluorescent.

FIGS. 11A-B are diagrams of an example of a light guide assembly 1100,according to aspects of the disclosure. The light guide assembly 1100includes a light guide 30 and a light extraction pattern formed on thesurface 34 of the light guide 30. The light extraction pattern includesa group G1 of light extraction elements 36 disposed between two groupsG2 of light extraction elements 38. Although in the present example thegroup G1 includes two columns of light extraction elements, alternativeimplementations are possible in which the group G1 includes any numberof columns of light extraction elements (e.g., 1, 5, 7, etc.). Althoughin the present example the groups G2 each include three columns of lightextraction elements, alternative implementations are possible in whicheach of the groups G2 includes any number of columns of light extractionelements (e.g., 2, 4, 7, etc.). Although in the present example thelight extraction pattern of the light guide 30 includes only threegroups of light extraction elements, alternative implementations arepossible in which the light guide 30 includes any number of lightextraction element groups (e.g., 2, 4, 5, 10, 15, etc.).

FIG. 11C is a candela diagram showing the light distribution patternproduced by the light guide assembly 1100. As illustrated, the lightguide assembly 1100 is configured to produce a modified batwing patternin both the upward and downward directions. This light distributionpattern has a more pronounced middle section than the light distributionpattern produced by the light guide assembly 700. This difference isattributable to the introduction of a minority of light extractionelements 38 that are grouped in the middle of the light guide 30.

According to aspects of the disclosure, all light extraction elements 36in the light guide assembly 1100 may have the same shape (e.g., acircular or dot shape) and the same size (e.g., a size in the range of0.01 mm-3 mm). Additionally or alternatively, all light extractionelements 38 in the light guide assembly 1100 may have the same shape(e.g., a circular or dot shape) and the same size (e.g., a size in therange of 0.01 mm-3 mm). Moreover, in the example of FIGS. 11A-C, eachlight extraction element 36 has the same size and/or shape as any of thelight extraction elements 38. However, alternative implementations arepossible in which each of the light extraction elements 36 has adifferent size than any of the light extraction elements 38.Additionally or alternatively, further implementations are possible inwhich each of the light extraction elements 36 has a different shapethan any of the light extraction elements 38. As discussed above, insome implementations, the light extraction elements 36 may differ intheir respective light reflectance and transmittance By way of example,each of the light extraction elements 38 may have 45% light reflectanceand 55% light transmittance, and a 15° Gaussian diffusion pattern, andthe light extraction elements 36 may each have 90% light reflectance and10% light transmittance. Furthermore, in some implementations, each ofthe light extraction elements 36 may have a uniform reflectance andtransmittance. Similarly, in some implementations, each of the lightextraction elements 38 may have a uniform reflectance and transmittance.And still furthermore, in some implementations, each of the lightextraction elements 36 and 38 may be non-fluorescent.

In the examples discussed with respect to FIGS. 10A-C and FIGS. 11A-C,the upward emissions produced by the light guide assemblies 1000 and1100, respectively, have the same distribution than the emissionsproduced in the downward direction. However, alternative implementationsare possible in which reflectors that only partially cover thesurface(s) of the light guide 30 are used to produce upward and downwardemissions that have different distributions. One such example isdiscussed further below with respect to FIGS. 12A-C.

FIGS. 12A-B are diagrams of an example of a light guide assembly 1200,according to aspects of the disclosure. The light guide assembly 1200includes the light guide 30 and a light extraction pattern formed on thesurfaces 32 and 34 of the light guide 30. The light extraction patternincludes a group G1 of light extraction elements 36 disposed between twogroups G2 of light extraction elements 38. In the present example, thegroups G2 of light extraction elements 38 are formed on the surface 32of the light guide 30, whereas the group G1 of light extraction elements36 is formed on the surface 34 of the light guide 30.

A different specular reflector 42 is placed over each of the groups G2on the surface 32 of the light guide 30. Each of the specular reflectors42 covers only a portion of the surface 32 of the light guide 30.Furthermore, each of the specular reflectors 42 covers the entire groupG2 it is placed over. For example, each specular reflector 42 may besituated directly above/below each of the light extraction elements 38in one of the groups G2 without extending under/over any of the lightextraction elements 36 in group G1. In the present example, light 37that is extracted by the light extraction elements 38 is reflected byspecular reflectors 42 towards the surface 34 of the light guide 30.

Furthermore, a diffusive reflector 40 is placed over group G1 on thesurface 34 of the light guide 30, as shown. The diffusive reflector 40covers only a portion of the surface 34 of the light guide 30 and it maybe situated directly above/below each of the light extraction elements36 without extending under/over any of the light extraction elements 38.In the present example, light 39 that is extracted by the lightextraction elements 36 is reflected by the diffusive reflector 40towards the surface 32 of the light guide 30.

Although in the present example the groups G1 and G2 of light extractionelements are printed on different surfaces of the light guide 30,alternative implementations are possible in which they are printed onthe same surface. Although in the present example the group G1 includesfour columns of light extraction elements, alternative implementationsare possible in which the group G1 includes any number of columns oflight extraction elements (e.g., 1, 5, 7, etc.). Although in the presentexample the groups G2 each include two columns of light extractionelements, alternative implementations are possible in which each of thegroups G2 includes any number of columns of light extraction elements(e.g., 1, 4, 7, etc.).

FIG. 12C is a candela diagram showing the light distribution patternproduced by the light guide assembly 1200. As illustrated, the lightguide assembly 1200 is configured to produce a batwing lightdistribution in the upward direction and a Lambertian light distributionin the downward direction. The batwing light distribution is produced bythe groups G2 of light extraction elements 38 in cooperation with thespecular reflectors 42, whereas the Lambertian light distribution isproduced by the group G1 of light extraction elements 36 in cooperationwith the diffusive reflector 40.

According to aspects of the disclosure, all light extraction elements 36in the light guide assembly 1200 may have the same shape (e.g., acircular or dot shape) and the same size (e.g., a size in the range of0.01 mm-3 mm). Additionally or alternatively, all light extractionelements 38 in the light guide assembly 1200 may have the same shape(e.g., a circular or dot shape) and the same size (e.g., a size in therange of 0.01 mm-3 mm). Moreover, in the example of FIGS. 12A-C, eachlight extraction element 36 has the same size and/or shape as any of thelight extraction elements 38. However, alternative implementations arepossible in which each of the light extraction elements 36 has adifferent size than any of the light extraction elements 38.Additionally or alternatively, further implementations are possible inwhich each of the light extraction elements 36 has a different shapethan any of the light extraction elements 38. As discussed above, insome implementations, the light extraction elements 36 may differ intheir respective light reflectance and transmittance. By way of example,each of the light extraction elements 38 may have 45% light reflectanceand 55% light transmittance, and a 15° Gaussian diffusion pattern, andthe light extraction elements 36 may each have 90% light reflectance and10% light transmittance. Furthermore, in some implementations, each ofthe light extraction elements 36 may have a uniform reflectance andtransmittance. Similarly, in some implementations, each of the lightextraction elements 38 may have a uniform reflectance and transmittance.And still furthermore, in some implementations, each of the lightextraction elements 36 and 38 may be non-fluorescent.

Although in the present example the light extraction pattern of thelight guide 30 includes only three groups of light extraction elements,alternative implementations are possible in which the light guide 30includes any number of light extraction element groups (e.g., 2, 4, 5,10, 15, etc.). In such instance, each group may be provided with aseparate reflector that is configured to reflect light extracted by thegroup in one of the upward and downward directions.

FIGS. 13A-B are diagrams of an example of a light guide assembly 1300,according to aspects of the disclosure. The light guide assembly 1300includes a light guide 30 and a light extraction pattern formed on asurface 34 of the light guide 30. The light extraction pattern includesa group G1 of light extraction elements 36 disposed between two groupsG2 of light extraction elements 38. A specular reflector 42 is disposedon the surface 34 of the light guide and arranged to cover the groups G1and G2. As a result, light 37 and 39 that is extracted by the lightextraction elements 38 and 36, respectively, is reflected down towardsthe surface 32 of the light guide 30, as shown.

Although in the present example the group G1 includes four columns oflight extraction elements, alternative implementations are possible inwhich the group G1 includes any number of columns of light extractionelements (e.g., 1, 5, 7, etc.). Although in the present example thegroups G2 each include two columns of light extraction elements,alternative implementations are possible in which each of the groups G2includes any number of columns of light extraction elements (e.g., 1, 4,7, etc.). Although in the present example the groups G1 and G2 extendalong the length of the light guide 30, alternative implementations arepossible in which the groups G1 and G2 extend along the width of thelight guide 30.

FIG. 13C is a candela diagram showing the light distribution patternproduced by the light guide assembly 1300. As illustrated, the lightguide assembly 1300 is operable to produce a light distribution patternin the downward direction only. The produced light distribution patternis a hybrid between a Lambertian light distribution pattern and abatwing light distribution pattern. The shape of the light distributionpattern is the result of combining a batwing light distribution patternproduced by the groups G2 of light extraction elements 38 (which mayhave the same distribution as the upward emissions shown in FIG. 12C)with a Lambertian light distribution pattern produced by the group G1 oflight extraction elements 36 (which may have the same distribution asthe downward emissions shown in FIG. 12C).

According to aspects of the disclosure, all light extraction elements 36in the light guide assembly 1300 may have the same shape (e.g., acircular or dot shape) and the same size (e.g., a size in the range of0.01 mm-3 mm). Additionally or alternatively, all light extractionelements 38 in the light guide assembly 1300 may have the same shape(e.g., a circular or dot shape) and the same size (e.g., a size in therange of 0.01 mm-3 mm). Moreover, in the example of FIGS. 13A-C, eachlight extraction element 36 has the same size and/or shape as any of thelight extraction elements 38. However, alternative implementations arepossible in which each of the light extraction elements 36 has adifferent size than any of the light extraction elements 38.Additionally or alternatively, further implementations are possible inwhich each of the light extraction elements 36 has a different shapethan any of the light extraction elements 38. As discussed above, insome implementations, the light extraction elements 36 may differ intheir respective light reflectance and transmittance. By way of example,each of the light extraction elements 38 may have 45% light reflectanceand 55% light transmittance, and a 15° Gaussian diffusion pattern, andthe light extraction elements 36 may each have 90% light reflectance and10% light transmittance. Furthermore, in some implementations, each ofthe light extraction elements 36 may have a uniform reflectance andtransmittance. Similarly, in some implementations, each of the lightextraction elements 38 may have a uniform reflectance and transmittance.And still furthermore, in some implementations, each of the lightextraction elements 36 and 38 may be non-fluorescent.

FIG. 14 is a diagram of an example of a light guide assembly 1400,according to aspects of the disclosure. The light guide assembly 1400includes the light guide 30 having a light extraction pattern formedthereon. The light extraction pattern includes a first grid pattern oflight extraction elements 36 and a second grid pattern of lightextraction elements 38. Each of the light extraction elements 36, exceptfor those adjacent to the edges of the light guide 30, is positioned ina different interstice between four different light extraction elements38. As used throughout the disclosure, the term “grid pattern” relatesto an arrangement of light extraction elements in which the lightextraction elements are arranged in vertical lines next to each other toform a matrix including a plurality of vertical columns and horizontalrows. Other examples of grid patterns are shown in FIGS. 4A-13A.

In some implementations, the light extraction elements 36 and the lightextraction elements may be arranged on the same surface of the lightguide 30. Alternatively, in some implementations the light extractionelements 36 may be arranged on a first surface of the light guide 30,and the light extraction elements 36 may be arranged on a second surfaceof the light guide 30 that is opposite the first surface.

According to aspects of the disclosure, all light extraction elements 36in the light guide assembly 1400 may have the same shape (e.g., acircular or dot shape) and the same size (e.g., a size in the range of0.01 mm-3 mm). Additionally or alternatively, all light extractionelements 38 in the light guide assembly 1400 may have the same shape(e.g., a circular or dot shape) and the same size (e.g., a size in therange of 0.01 mm-3 mm). Moreover, in the example of FIG. 14, each lightextraction element 36 has a different size and/or shape as any of thelight extraction elements 38. However, alternative implementations arepossible in which each of the light extraction elements 36 has the samesize than any of the light extraction elements 38. Additionally oralternatively, further implementations are possible in which each of thelight extraction elements 36 has a different shape than any of the lightextraction elements 38. As discussed above, in some implementations, thelight extraction elements 36 may differ in their respective lightreflectance and transmittance. By way of example, each of the lightextraction elements 38 may have 45% light reflectance and 55% lighttransmittance, and a 15° Gaussian diffusion pattern, and the lightextraction elements 36 may each have 90% light reflectance and 10% lighttransmittance. Furthermore, in some implementations, each of the lightextraction elements 36 may have a uniform reflectance and transmittance.Similarly, in some implementations, each of the light extractionelements 38 may have a uniform reflectance and transmittance. And stillfurthermore, in some implementations, each of the light extractionelements 36 and 38 may be non-fluorescent.

FIG. 15 is a candela diagram showing the light distribution patternproduced by the light guide assembly 1400. As illustrated, the lightguide assembly 1400 is configured to produce a batwing lightdistribution in the upward direction and a Lambertian light distributionin the downward direction. Approximately 30% of the light emitted by thelight guide assembly 1400 is directed upwards, while 70% of the lightemitted by the light guide assembly 1400 is directed downwards. In someimplementations, the ratio of upward light to downward light may beincreased or decreased by changing at least one of: (i) the relativesize of the light extraction elements 36 and 38, (ii) the area coveredby each of the light extraction elements 36 and 38, and (iii) thedistribution density of the light extraction elements 36 and 38. In someimplementations, the distribution density of the light extractionelements 36 or 38 may be based on (e.g., equal to) the count of lightextraction elements per unit area (e.g., cm²).

FIGS. 1-15 are provided as an example only. Although in the examplesprovided with respect to FIGS. 1-15, the light extraction elements 36and 38 are arranged in straight lines to form a rectangular matrix,alternative implementations are possible in which the light extractionelements 36 are arranged in any suitable manner. For example, the lightextraction elements 36 and 38 may be arranged in other arrays besidesrectangular matrices. As another example, the light extraction elements36 and 38, in any of the light guide assemblies discussed above, may bearranged in random or pseudo-random arrangements. As yet anotherexample, the light extraction elements 36 and 38, in any of the lightguide assemblies discussed above, may be arranged patterns that cover anentire surface(s) of the light guide 30 without there being any gapsbetween them that are not covered. As can readily be appreciated, ininstances in which an entire surface of the light guide 30 is covered,the light extraction elements 36 and 38 may have different shapes.Furthermore, in any of the examples discussed above, at least one lightextraction element 36 in a given light guide assembly may have adifferent size and/or shape than another light extraction element 36 inthe same light guide assembly. Similarly, in any of the examplesdiscussed above, at least one light extraction element 38 in a givenlight guide assembly may have a different size and/or shape than anotherlight extraction element 38 in the same light guide assembly.

At least some of the elements discussed with respect to these figurescan be arranged in different order, combined, and/or altogether omitted.It will be understood that the provision of the examples describedherein, as well as clauses phrased as “such as,” “e.g.”, “including”,“in some aspects,” “in some implementations,” and the like should not beinterpreted as limiting the disclosed subject matter to the specificexamples.

Having described the invention in detail, those skilled in the art willappreciate that, given the present disclosure, modifications may be madeto the invention without departing from the spirit of the inventiveconcepts described herein. Therefore, it is not intended that the scopeof the invention be limited to the specific embodiments illustrated anddescribed.

What is being claimed is:
 1. A light-emitting system, comprising: alight guide configured to guide light received from a light source; afirst light extraction element positioned on a first surface of thelight guide and configured to extract a portion of the guided light fromthe light guide, the first light extraction element having a firstreflectance and a first transmittance; and a second light extractionelement positioned on the first surface of the light guide andconfigured to extract a portion of the guided light from the lightguide, the second light extraction element having a second reflectancedifferent from the first reflectance, the second light extractionelement having a second transmittance different from the firsttransmittance.
 2. The light-emitting system of claim 1, wherein: thefirst light extraction element being printed on the first surface of thelight guide with a first ink; and the second light extraction elementbeing printed on the first surface of the light guide with a second inkdifferent from the first ink.
 3. The light-emitting system of claim 1,wherein the first light extraction element is configured such that lightextracted from the light guide by the first light extraction element hasan angular distribution that is approximately Lambertian.
 4. Thelight-emitting system of claim 1, wherein the first reflectance and thefirst transmittance sum to about 100%.
 5. The light-emitting system ofclaim 1, wherein the first reflectance is about 90% and the firsttransmittance is about 10%.
 6. The light-emitting system of claim 1,wherein the second light extraction element is configured such thatlight extracted from the light guide by the second light extractionelement has an angular distribution that is approximately batwing. 7.The light-emitting system of claim 1, wherein the second reflectance andthe second transmittance sum to about 100%.
 8. The light-emitting systemof claim 1, wherein the second reflectance is about 45% and the secondtransmittance is about 55%.
 9. The light-emitting system of claim 8,wherein the second light extraction element is configured to have aGaussian diffusion pattern of about 15 degrees.
 10. The light-emittingsystem of claim 1, wherein: the first light extraction element isconfigured such that light extracted from the light guide by the firstlight extraction element has an angular distribution that isapproximately Lambertian; the second light extraction element isconfigured such that light extracted from the light guide by the secondlight extraction element has an angular distribution that isapproximately batwing; and the first surface of the light guide isconfigured such that light extracted from the light guide by the firstlight extraction element and the second light extraction element,combined, has an angular distribution that is wider than Lambertian andnarrower than batwing.
 11. The light-emitting system of claim 1, furthercomprising: a first plurality of light extraction elements positioned onthe first surface of the light guide, the first plurality of lightextraction elements including the first light extraction element, eachlight extraction element of the first plurality having a reflectancethat equals the first reflectance and a transmittance that equals thefirst transmittance; and a second plurality of light extraction elementspositioned on the first surface of the light guide, the second pluralityof light extraction elements including the second light extractionelement, each light extraction element of the second plurality having areflectance that equals the second reflectance and a transmittance thatequals the second transmittance.
 12. The light-emitting system of claim11, wherein: the first plurality of light extraction elements areconfigured such that light extracted from the light guide by each firstlight extraction element has an angular distribution that isapproximately Lambertian; the second plurality of light extractionelements are configured such that light extracted from the light guideby each second light extraction element has an angular distribution thatis approximately batwing; and the first surface of the light guide isconfigured such that light extracted from the light guide by the firstplurality of light extraction elements and the second plurality lightextraction elements, combined, has an angular distribution that is widerthan Lambertian and narrower than batwing.
 13. The light-emitting systemof claim 1, further comprising the light source, the light sourceconfigured to inject light into the light guide through an edge of thelight guide.
 14. The light-emitting system of claim 1, furthercomprising the light source, the light source being positioned in acavity in the light guide and configured to inject light into the lightguide through one or more walls of the cavity.
 15. A method for emittinglight, the method comprising: receiving, with a light guide, light froma light source; guiding, with the light guide, a first portion of thereceived light to a first light extraction element positioned on a firstsurface of the light guide, the first light extraction element having afirst reflectance and a first transmittance; extracting, from the lightguide, a second portion of the light with the first light extractionelement; guiding, with the light guide, a third portion of the receivedlight to a second light extraction element positioned on the firstsurface of the light guide, the second light extraction element having asecond reflectance different from the first reflectance, the secondlight extraction element having a second transmittance different fromthe first transmittance; and extracting, from the light guide, a fourthportion of the light with the second light extraction element.
 16. Themethod of claim 15, wherein: the second portion comprises the firstportion, multiplied by the first transmittance; and the fourth portioncomprises the third portion, multiplied by the second transmittance. 17.The method of claim 15, further comprising: reflecting, with the firstlight extraction element, a fifth portion of light such that the fifthportion remains in the light guide; and reflecting, with the secondlight extraction element, a sixth portion of light such that the sixthportion remains in the light guide.
 18. The method of claim 17, wherein:the fifth portion comprises the first portion, multiplied by the firstreflectance; and the sixth portion comprises the third portion,multiplied by the second reflectance.
 19. The method of claim 15,wherein the second light extraction element is configured to have aGaussian diffusion pattern of about 15 degrees, and further comprising:angularly broadening the light with the second light extraction element,such that the fourth portion of the light has an angular distributionthat is wider than an angular distribution of the second portion of thelight.
 20. A light-emitting system, comprising: a light sourceconfigured to produce light; a light guide configured to receive lightfrom the light source and guide the received light; a plurality of firstlight extraction elements positioned on a first surface of the lightguide, each first light extraction element configured to extract aportion of the guided light from the light guide, the first lightextraction elements having a same first reflectance and a same firsttransmittance, each first light extraction element being printed on thefirst surface with a first ink; and a plurality of second lightextraction elements positioned on the first surface of the light guide,each second light extraction element configured to extract a portion ofthe guided light from the light guide, each second light extractionelement having a second reflectance different from the firstreflectance, each second light extraction element having a secondtransmittance different from the first transmittance, each second lightextraction element being printed on the first surface with a second inkdifferent from the first ink.